intended prefix becomes title instead

I am running Private Suite 2.1 with the Scrawl theme and WP 4.5.2.

Private Suite does indeed make posts of a checked category automatically private.

However, its other function doesn’t work for me. Instead of the “Prefix for private post and page titles:” becoming a prefix, the text I enter in that box becomes the title of every private post.

<blank> causes no title to appear on any private post
“Private:” casues the “Private:” to be the title on every private post

Is there something else I should try?

https://wordpress.org/plugins/private-suite/